1. Field of The Invention
The present invention relates to a system and process for generating steam and supplying the steam to steam-using devices.
2. State of the Art
Steam needed for industrial processes is normally generated by boilers and then distributed via conduits called headers. Often steam-using devices in a facility require steam at various pressures and thus a steam distribution system often includes multiple headers at different steam pressures. The steam can be transferred from one header to another via turbines and partially expanded via the turbines to the desired pressure levels. During expansion through the turbines, some thermal steam energy is converted into mechanical energy and then, via generators, into electrical energy. The conversion of heat into electrical energy occurs with high efficiency, and therefore, partial expansion of steam in turbines and generation of electrical energy, called cogeneration, is very popular.
The pressure at each header must be regulated, and the industry practice has often been such that, devices supplying a header are controlled to provide pressure regulation for that header. For example, boilers are regulated to control the pressure at the headers which they supply. Also, turbines have a pressure regulator at their extraction stages. And when a turbine is used to transfer steam from a high-pressure header to a lower pressure header, the pressure regulator is operated to control the pressure at the lower pressure header.
Computerized systems have been used to control boilers which supply a header. However, such systems have been limited in that they can control the steam pressure at only a single header without regard to the effects of such control upon the pressure in other headers.